This invention relates to valves.
Closed system suction catheter assemblies are used for removing secretions from within the trachea or bronchii of an intubated patient. The assembly comprises a flexible catheter connected at its machine end with a fitting including a valve that can be opened or closed to control the application of suction to the catheter. The valve is usually of a kind having a valve member movable laterally of a flow path between two positions where flow is either enabled or prevented.
Towards its patient end, the catheter extends through a forward, patient end fitting connected between the end of a tracheal tube and a ventilation circuit. The catheter can be advanced through the forward coupling down the tracheal tube to enable suctioning. A flexible envelope extends between the two couplings, enclosing the catheter so that it can be manipulated through the envelope. A wiper seal in the forward coupling prevents gas from the ventilation system inflating the envelope. Assemblies of this kind are sold by Portex, Inc under the trade mark STERI-CATH®, by Ballard Medical, Inc/Kimberly-Clark under the trade mark TRACH-CARE® and by Sorenson Critical Care, Inc. In some assemblies, provision is made for cleaning the catheter after its patient end has been withdrawn into the forward coupling. A manually-operable valve is located forwardly of the wiper seal providing a cleaning chamber between the valve and the wiper seal. An irrigation port opens into this chamber so that saline can be supplied to it, which is then drawn along the bore of the catheter by the applied suction to remove matter collected within the bore.
The valve used to close the washing chamber could be of various different kinds. U.S. Pat. No. 5,354,267 and U.S. Pat. No. 5,882,348 describe rotary stop-cock type valves, which are turned either to isolate the cleaning chamber from the patient end of the coupling or to enable the catheter to be advanced through the valve into the trachea. An alternative form of valve is described in U.S. Pat. No. 5,775,325. This valve is of the duck-bill type within an integral, deformable outer tube. The valve has a normally-closed slit and this is opened by squeezing the sides of the outer tube together parallel to the length of the slit. This valve has certain advantages because it can be made as an integral component. However, it also has a number of disadvantages. In particular, the valve has to be held open continuously manually while the catheter is advanced. This can be tiring in prolonged operation and means that the user has to occupy one hand maintaining the valve open. There is also a risk that the valve may not be held fully open during extension of the catheter. This could cause dragging on the catheter and may wipe secretions from the outside of the catheter in a position where they could move back into the airway. Furthermore, there is a risk that twisting or bending the assembly in the region of the cleaning chamber could inadvertently open the valve. U.S. Pat. No. 6,543,451 describes a valve opened by advancing the catheter. This valve rubs along the outside of the catheter as it is withdrawn and may also dislodge secretions.